Giglioti R, Oliveira H N, Santana C H, Ibelli A M G, Néo T A, Bilhassi T B, Rabelo M D, Machado R Z, Brito L G, Oliveira M C S
Universidade Estadual Júlio de Mesquita Filho, Jaboticabal, SP, Brazil.
Universidade Estadual Júlio de Mesquita Filho, Jaboticabal, SP, Brazil.
Ticks Tick Borne Dis. 2016 Jul;7(5):657-662. doi: 10.1016/j.ttbdis.2016.02.011. Epub 2016 Feb 11.
The levels of infection by Babesia bovis and Babesia bigemina were estimated by absolute quantification through the quantitative PCR technique (qPCR). Fifty-one contemporaneous Angus cattle were evaluated on two occasions. The number of standard female Rhipicephalus microplus ticks present on the left side of the body was counted and blood samples were drawn from the tail vein into tubes containing the anticoagulant EDTA. The blood samples were submitted to DNA extraction and used to quantify the number of copies (NC) of DNA from B. bovis and B. bigemina by qPCR. The data on tick count and number of DNA copies were transformed for normalization and analyzed by a mixed model method. A multivariate model with repeated measures of the same animal, including the effects of collection, parasite species and their interaction, was used. The repeatability values were obtained from the matrix of (co)variances and were expressed for each species. The correlations between the counts of different species on the same animal, in the same collection or different collections, were also estimated. The results showed the qPCR could distinguish the two between infection by the two Babesia species. Infection levels by B. bovis and B. bigemina were detected in 100% and 98% of the animals, respectively. Significant differences were found (P<0.05) between the NC of the two Babesia species, B. bovis 1.49±0.07 vs. B. bigemina 0.82±0.06. Low repeatabilities were found for the counts of R. microplus and NC of B. bovis and B. bigemina: 0.05, 0.10 and 0.02, respectively. The correlations between R. microplus count and NC of B. bovis and B. bigemina were both very near zero. However, an association was observed between the NC of the two species, with a correlation coefficient of 0.30 for measures from the same collection. The absence of associations between the quantity of DNA from B. bovis and B. bigemina and the tick counts suggests that the variation of parasitemia by the hemoparasites did not depend on the tick infestation levels at the moment of each collection. The repeatability values estimated indicate that under the study conditions, the variations in the tick infestation levels and of parasitemia by B. bovis and B. bigemina depend more on factors related to each collection than on intrinsic factors of the animal.
通过定量聚合酶链反应技术（qPCR）进行绝对定量，估算牛巴贝斯虫和双芽巴贝斯虫的感染水平。对51头同期的安格斯牛进行了两次评估。统计牛体左侧微小扇头蜱标准雌蜱的数量，并从尾静脉采集血样至含有抗凝剂乙二胺四乙酸（EDTA）的试管中。血样进行DNA提取，并用于通过qPCR定量牛巴贝斯虫和双芽巴贝斯虫的DNA拷贝数（NC）。蜱计数和DNA拷贝数数据进行转换以实现标准化，并采用混合模型方法进行分析。使用了一个包含同一动物重复测量的多变量模型，包括采集、寄生虫种类及其相互作用的影响。重复性值从（协）方差矩阵中获得，并针对每个物种表示。还估算了同一动物、同一采集或不同采集中不同物种计数之间的相关性。结果表明，qPCR能够区分两种巴贝斯虫的感染情况。分别在100%和98%的动物中检测到牛巴贝斯虫和双芽巴贝斯虫的感染水平。两种巴贝斯虫的NC之间存在显著差异（P<0.05），牛巴贝斯虫为1.49±0.07，双芽巴贝斯虫为0.82±0.06。微小扇头蜱计数以及牛巴贝斯虫和双芽巴贝斯虫的NC的重复性较低，分别为0.05、0.10和0.02。微小扇头蜱计数与牛巴贝斯虫和双芽巴贝斯虫的NC之间的相关性均非常接近零。然而，观察到两种物种的NC之间存在关联，同一采集中测量的相关系数为0.30。牛巴贝斯虫和双芽巴贝斯虫的DNA量与蜱计数之间不存在关联，这表明血液寄生虫的寄生虫血症变化并不取决于每次采集时的蜱感染水平。估算的重复性值表明，在研究条件下，微小扇头蜱感染水平以及牛巴贝斯虫和双芽巴贝斯虫的寄生虫血症变化更多地取决于与每次采集相关的因素，而非动物的内在因素。
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